In conventional cellular networks or Wireless Local Area Networks (WLANs), service quality is secured by controlling error rates and transmission speeds by varying control parameters in the physical layers (PHY) in accordance with the states of wireless transmission paths, or controlling retransmission and congestion through Medium Access Control (MAC). However, the control is not sufficient.
In a communication environment with poor line quality, throughput is low. For example, Patent Document 1 discloses a method of measuring or estimating line quality. In an environment with low throughput, services are preferably provided at low prices. In an environment with high throughput, services are preferably provided at high prices.
There have been systems with which speed restrictions are lifted upon payment of additional charge (with a coupon). For example, a user pays for the coupon, and manually validates the coupon on the Internet through a personal computer (PC), so that the speed restrictions are lifted.